(Bloomberg) -- U.K. police warned that children as young as 14 years-old are being enticed into far-right chatrooms and quickly radicalized by extremists online.

The most radical groups have moved away from mainstream social media platforms such as Twitter and Facebook to darker, more secure parts of the internet, Metropolitan Police Assistant Commissioner Neil Basu said in London on Thursday.

“People are radicalized in days or weeks,” Basu, who heads up U.K. counter-terrorism policing, told reporters. “The lone actor threat is the biggest problem.”

Islamist terrorism still dominates counter-terrorism investigations, but far-right extremism is the fastest growing trend, taking up about 10% of police time on the 800 or so live inquiries, Basu said.

“The people who are doing this are very 21st century internet-savvy people,” he said. Extremists are drawing inspiration from Islamic State’s strategy of driving mainstream social media traffic to invitation-only chatrooms, he said.

Far-right groups don’t draw their ideologies solely from an anti-Islam or racist ideology, Basu said. A mixed set of grievances including Brexit, fringe religious groups and anti-state ideology are also being used to drive the radicalization that leads to terrorist attacks.

“Who would have thought that satanism is an ideology that we’d have to understand?” Basu said.

To contact the reporter on this story: Kitty Donaldson in London at kdonaldson1@bloomberg.net

To contact the editors responsible for this story: Tim Ross at tross54@bloomberg.net, Thomas Penny, Stuart Biggs

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